Many functions of modern devices in automotive, consumer and industrial applications, such as converting electrical energy and driving an electric motor or an electric machine, rely on semiconductor devices. For example, Insulated Gate Bipolar Transistors (IGBTs), Metal Oxide Semiconductor Field Effect Transistors (MOSFETs) and diodes, to name a few, have been used for various applications including, but not limited to switches in power supplies and power converters.
It is a general aim to keep losses occurring at semiconductor devices low, wherein said losses essentially are caused by conducting losses and/or switching losses.
For example, a power semiconductor device comprises a plurality of MOS control heads, wherein each control head may have at least one control electrode and a source region and a channel region arranged adjacent thereto.
For setting the power semiconductor device into a conducting state, during which a load current in a forward direction may be conducted, the control electrode may be provided with a control signal having a voltage within a first range so as to induce a load current path within the channel region.
For setting the power semiconductor device into a blocking state, during which a forward voltage applied to load terminals of the semiconductor device may be blocked and flow of the load current in the forward direction is inhibited, the control electrode may be provided with the control signal having a voltage within a second range different from the first range so as to cut off the load current path in the channel region. Then, the forward voltage may induce a depletion region at a junction formed by a transition between the channel region and a drift region of the power semiconductor device, wherein the depletion region is also called “space charge region” and may mainly expand into the drift region of the semiconductor device. In this context, the channel region is frequently also referred to as a “body region”, in which said load current path, e.g., an inversion channel, may be induced by the control signal to set the semiconductor device in the conducting state. Without the load current path in the channel region, the channel region may form a blocking junction with the drift region.
In the conducting state, a lower limit of a forward voltage drop may be determined by a forward biased diode of the power semiconductor device, such as at a transition between an n-doped drift region and a p-doped emitter region on the collector side of an IGBT. It may be desirable to overcome this limitation on the forward voltage in operation so as further minimize losses in the conducting state.